International Agency for Research on Cancer (IARC) - Summaries & Evaluations

LUMBER AND SAWMILL INDUSTRIES (INCLUDING LOGGING)(Group 3)

Information on the occurrence of cancer in lumber and sawmill
workers is limited. The available epidemiological data come primarily
from surveys of statements of occupation on death certificates. Nasal
tumours, malignant lymphomas and leukaemias and soft-tissue sarcomas
have been linked with work in the lumber and sawmill industries, but
the results are not consistent [ref: 1].

In a case-control study based on an analysis of occupational data
in the hospital records of 121 men seen for nasal cancer in British
Columbia, Canada, between 1939 and 1977, a relative risk of 2.5
(adjusted for smoking and ethnic origin) was found to be associated
with exposure to wood. There was increased risk for most histological
types of epithelial tumour, except for transitional tumours. Of the
28 wood workers with nasal cancer, 16 had worked in the forestry
industry, seven had been carpenters, four had been construction
workers and one had been a cabinet-maker [ref: 2].

In a case-control study based on 167 cases of nasal or sinonasal
cancer and 167 controls from Denmark, Finland and Sweden, exposure
mainly to softwood dust (pine and spruce, but also some birch) was
associated with epidermoid and anaplastic carcinomas, but not with
adenocarcinomas. There were 13 cases with exposure only to softwood
versus four controls (odds ratio, 3.3; 95% confidence interval,
1.1-9.4). Of these, four cases (all with epidermoid carcinoma) and
two controls had been sawmill workers. Only two of the four cases had
had potential exposure to chlorophenols [ref: 3].

In a Norwegian study based on 70 cases of various forms of
sinonasal cancer (4 cases observed, 0.4 expected in saw- and
planingmill workers; 3 observed, 1.8 expected in forestry workers),
three cases of non-Hodgkin's lymphoma were associated with employment
in saw- and planingmill firms. The comparison was made beween the
number of cases observed in different occupations and the expected
number of cases according to the 1946 census data of workers in these
occupations [ref: 4].

A case-control study of Hodgkin's disease [ref: 5], using death
certificates from North Carolina, USA, counties with a 'significant
proportion' of the population employed in the furniture industry and
in lumbering, showed an excess risk only among occupational groups
with exposure to wood or paper. Carpenters and lumberers had a
relative risk of 4.2 for Hodgkin's disease (95% confidence interval,
1.4-12.5). In Oregon, USA, a case-control study on leukaemia
(ICD-9 codes 204-208) [ref: 6] showed a three-fold increase in risk
for patients who had worked for ten years or more in the sawmill
industry (p = 0.017), based on nine exposed cases.

In a proportionate mortality study of the causes of death of 375
union-affiliated Swedish lumberjacks who had died between 1968 and
1977, there were fewer deaths from cancer than expected (PMR, 88;
69-111). A marked deficiency of deaths from lung cancer (SMR, 33) and
excesses of deaths from kidney cancer (SMR, 193; 92-407) and from
cancers of the lymphatic and haematopoietic systems (SMR, 191;
105-349) were found. No information was given about the histology of
these two groups of tumours. The mortality experience of Swedish
males during that period was used as the standard for comparison [ref:
7].

A cohort study comparing the mortality experience of 10 322 men
employed in the wood working industries with that of 406 798 non-wood
workers showed no excess risk for all cancers combined. In the
subcohort of lumber and sawmill workers, there was no statistically
significantly increase in the incidence of cancer at any site. No
case of nasal cancer was reported [ref: 8].

A nested case-control study [ref: 9], based on an average of 25
years' follow-up of 3805 men working in the Finnish particle-board,
plywood, sawmill or formaldehyde glue industries between 1944 and
1965, showed no clear connection between respiratory cancer incidence
and most of the exposures studied, although some odds ratios were
statistically significantly increased. For example, exposure to
pesticides (in wood dust) and phenol was associated with elevated odds
ratios, which became more marked among workers with more than ten
years' exposure to pesticides. The raised odds ratios for exposure to
phenol were partly explained by smoking and exposure to pesticides.
Because of the mixed exposure, no single pesticide could be linked
with respiratory cancer. Exposure to terpenes and other products of
coniferous wood was also significantly associated with respiratory
cancer when the duration of exposure exceeded five years. None of the
odds ratios for exposure to wood dust and chlorophenols was
statistically significant.

A proportionate mortality study showed an elevated risk for death
from all cancers (proportionate mortality ratio [PMR], 112; p <0.01),
stomach cancer (PMR, 128; p <0.01) and non-Hodgkin's lymphoma (PMR,
139; p <0.05) among woodworkers (including carpenters, cabinet and
furniture workers, lumber graders and scalers, sawyers in sawmills and
woodworkers not classified elsewhere). In this mixed category, there
was no death from sinonasal cancer [ref: 10].

The epidemiological data reported here and previously [ref: 1]
are not sufficient to make a definite assessment of the carcinogenic
risks of employment in the lumber and sawmill industries. It should
also be noted that these two industries differ greatly with regard to
exposures other than wood dust. Some studies suggest that the
incidences of nasal cancers, lung cancer and Hodgkin's and
non-Hodgkin's lymphoma may be increased. The patterns are not
consistent, the results are based on few cases and, in some studies,
work in furniture manufacture has not been excluded sufficiently well.
The hypothesis of a link with Hodgkin's disease is not adequately
supported. Soft-tissue sarcomas and histiocytic lymphomas have been
reported following exposure to chlorophenols and phenoxyacetic acid
herbicides, but the risk to sawmill and lumber
workers was not quantified directly. Stomach cancer incidence was
slightly elevated in these occupational groups in six mortality
series; however, this might be related to nonoccupational factors.

Overall evaluation

Lumber and sawmill industries (including logging) entail exposures that are not classifiable as to their carcinogenicity to humans (Group 3).